In theory, if the servers reflected active populations then you could pick any server and still enjoy the game.
On initial release people screamed on the forums that server queue times were too long and for EA/BW to open more servers. Unfortunately EA/BW got ahead of themselves (too cocky?) and opened too many servers so when the active population contracted there were dead servers everywhere. In turn that put more people off and the populations continued to decrease. Don't get me wrong, the overall population is still arguably healthy. The official active subs is still quoted at around 1.3mil, it's just that the population is spread between too many servers.